The EUSO-SPB2 Cherenkov Telescope -- Flight Performance and Preliminary Results

Abstract

Astrophysical Very-High-Energy (VHE, >10PeV) neutrinos deliver crucial information about the sources of Ultra-High-Energy Cosmic Rays (UHECRs), the composition of UHECRs, and neutrino/particle physics at highest energies. UHE-tau neutrinos skimming the Earth's surface produce tau leptons, which can emerge from the ground, decay, and start an upward-going extensive air shower (EAS) in the Earth's atmosphere. The tau neutrino can be reconstructed by imaging the EAS. We developed an atmospheric Cherenkov Telescope flying on the Extreme Universe Space Observatory Super Pressure Balloon 2 (EUSO-SPB2) mission to test the air-shower imaging concept at highest altitudes. The EUSO-SPB2 ultra-long-duration balloon mission is a precursor of the Probe of Extreme Multi-Messenger Astrophysics (POEMMA), a candidate for an astrophysics probe-class mission. The telescope implements Schmidt optics with a 0.785 m^2 light collection area and a 512-pixel SiPM camera covering a 12.8° by 6.4° (Horizontal by Vertical) field-of-view with 0.4° resolution. The camera signals are sampled with 100MSa/s and digitized with 12-bit resolution. The objectives of the EUSO-SPB2 Cherenkov telescope include a search for UHE neutrinos below Earth's limb, UHECRs above the limb, the study of the night sky background, and studying the telescope's performance. In this presentation, I will present an overview of the Cherenkov telescope and discuss the in-flight performance of the telescope.